scholarly journals Behavior of Saline Ice under Cyclic Flexural Loading

2020 ◽  
Author(s):  
Andrii Murdza ◽  
Erland M. Schulson ◽  
Carl E. Renshaw
Keyword(s):  
Cyclic Loading ◽  
Flexural Strength ◽  
Stress Amplitude ◽  
Crack Nucleation ◽  
Back Stress ◽  
Lake Ice ◽  
Hit Rate ◽  
Vertical Location ◽  
Dislocation Pileups ◽  
Reversed Cyclic

Abstract. New systematic experiments reveal that the flexural strength of saline S2 columnar-grained ice loaded normal to the columns can be increased upon cyclic loading by about a factor of 1.5. The experiments were conducted using reversed cyclic loading over ranges of frequencies from 0.1 to 0.6 Hz and at a temperature of −10 ºC on saline ice of two salinities: 3.0±0.9 and 5.9±0.6 ‰. Acoustic emission hit rate during cycling increases with an increase of stress amplitude of cycling. Flexural strength of saline ice of 3.0±0.9 ‰ salinity appears to increase linearly with increasing stress amplitude, similar to the behavior of laboratory-grown freshwater ice (Murdza et al., 2020c) and to the behavior of lake ice (Murdza et al., 2020a). The flexural strength of saline ice of 5.9±0.6 ‰ depends on the vertical location of the sample within the thickness of an ice puck; i.e., the strength of the upper layers, which have a lower brine content, was found to be as high as three times that of lower layers. Flexural strength is governed by tensile strength which appears to be controlled by crack nucleation. Cyclic strengthening is attributed to the development of an internal back stress that opposes the applied stress and originates possibly from dislocation pileups. The fatigue life of saline ice is erratic.

scholarly journals Behavior of saline ice under cyclic flexural loading

2021 ◽  
Vol 15 (5) ◽  
pp. 2415-2428
Author(s):  
Andrii Murdza ◽  
Erland M. Schulson ◽  
Carl E. Renshaw
Keyword(s):  
Acoustic Emission ◽  
Cyclic Loading ◽  
Flexural Strength ◽  
Stress Amplitude ◽  
Back Stress ◽  
Lake Ice ◽  
Hit Rate ◽  
Vertical Location ◽  
Dislocation Pileups ◽  
Reversed Cyclic

Abstract. New systematic experiments reveal that the flexural strength of saline S2 columnar-grained ice loaded normal to the columns can be increased upon cyclic loading by about a factor of 1.5. The experiments were conducted using reversed cyclic loading over ranges of frequencies from 0.1 to 0.6 Hz and at a temperature of −10 ∘C on saline ice of two salinities: 3.0 ± 0.9 and 5.9 ± 0.6 ‰. Acoustic emission hit rate during cycling increases with an increase in stress amplitude of cycling. Flexural strength of saline ice of 3.0 ± 0.9 ‰ salinity appears to increase linearly with increasing stress amplitude, similar to the behavior of laboratory-grown freshwater ice (Murdza et al., 2020b) and to the behavior of lake ice (Murdza et al., 2021). The flexural strength of saline ice of 5.9 ± 0.6 ‰ depends on the vertical location of the sample within the thickness of an ice puck; i.e., the strength of the upper layers, which have a lower brine content, was found to be as high as 3 times that of lower layers. The fatigue life of saline ice is erratic. Cyclic strengthening is attributed to the development of an internal back stress that opposes the applied stress and possibly originates from dislocation pileups.

scholarly journals Strengthening of columnar-grained freshwater ice through cyclic flexural loading

2020 ◽  
Vol 66 (258) ◽  
pp. 556-566 ◽  
Author(s):  
Andrii Murdza ◽  
Erland M. Schulson ◽  
Carl E. Renshaw
Keyword(s):  
Cyclic Loading ◽  
Flexural Strength ◽  
Tensile Stress ◽  
Applied Stress ◽  
Stress Amplitude ◽  
Crack Nucleation ◽  
Back Stress ◽  
Maximum Tensile Stress ◽  
Reversed Cyclic ◽  
Fundamental Requirement

AbstractSystematic experiments reveal that the flexural strength of freshwater S2 columnar-grained ice loaded normal to the columns increases upon cyclic loading. Specifically, over the range of stress amplitudes 0.1–2.6 MPa the flexural strength increases linearly with increasing stress amplitude. The experiments were conducted upon both reversed and non-reversed cyclic loading over ranges of frequencies from 0.03 to 2 Hz and temperatures from −25 to −3°C. Strengthening can also be imparted through bending-induced creep. The fundamental requirement for strengthening is that the surface that undergoes maximum tensile stress during failure must have been pre-stressed in tension. Flexural strength is governed by crack nucleation. We suggest that the process is resisted by an internal back-stress that opposes the applied stress and builds up through either crystal dislocations piling up or grain boundaries sliding.

scholarly journals Cyclic strengthening of lake ice

2020 ◽  
pp. 1-4
Author(s):  
Andrii Murdza ◽  
Aleksey Marchenko ◽  
Erland M. Schulson ◽  
Carl E. Renshaw
Keyword(s):  
Flexural Strength ◽  
Fresh Water ◽  
Stress Amplitude ◽  
Fiber Stress ◽  
Lake Ice ◽  
Water Ice ◽  
Outer Fiber

Abstract Further to systematic experiments on the flexural strength of laboratory-grown, fresh water ice loaded cyclically, this paper describes results from new experiments of the same kind on lake ice harvested in Svalbard. The experiments were conducted at −12 °C, 0.1 Hz frequency and outer-fiber stress in the range from ~ 0.1 to ~ 0.7 MPa. The results suggest that the flexural strength increases linearly with stress amplitude, similar to the behavior of laboratory-grown ice.

scholarly journals Strengthening ice through cyclic loading

2017 ◽  
Vol 63 (240) ◽  
pp. 663-669 ◽  
Author(s):  
DANIEL ILIESCU ◽  
ANDRII MURDZA ◽  
ERLAND M. SCHULSON ◽  
CARL E. RENSHAW
Keyword(s):  
Stress Concentration ◽  
Cyclic Loading ◽  
Flexural Strength ◽  
Grain Boundary ◽  
Fresh Water ◽  
Grain Boundary Sliding ◽  
Reversed Cyclic Loading ◽  
Induced Stress ◽  
Boundary Sliding ◽  
Reversed Cyclic

ABSTRACTNew experiments reveal that the flexural strength of fresh water, columnar-grained ice loaded normal to the columns may be increased by about a factor of two upon reversed cyclic loading at a frequency of ~0.1 Hz at stress amplitudes of 1.3–2.6 MPa. The effect is explained in terms of a reduction in deformation-induced stress concentration through the activation of grain boundary sliding, which is evident through boundary decohesion.

Comparative study of the effective parameters on residual stress relaxation in welded aluminum plates under cyclic loading

2020 ◽  
Vol 21 (5) ◽  
pp. 505
Author(s):  
Yousef Ghaderi Dehkordi ◽  
Ali Pourkamali Anaraki ◽  
Amir Reza Shahani
Keyword(s):  
Residual Stress ◽  
Cyclic Loading ◽  
Stress Relaxation ◽  
Stress Amplitude ◽  
Cyclic Plasticity ◽  
Mean Stress ◽  
Effective Parameters ◽  
Perfect Plasticity ◽  
Residual Stress Relaxation ◽  
Aluminum Plates

The prediction of residual stress relaxation is essential to assess the safety of welded components. This paper aims to study the influence of various effective parameters on residual stress relaxation under cyclic loading. In this regard, a 3D finite element modeling is performed to determine the residual stress in welded aluminum plates. The accuracy of this analysis is verified through experiment. To study the plasticity effect on stress relaxation, two plasticity models are implemented: perfect plasticity and combined isotropic-kinematic hardening. Hence, cyclic plasticity characterization of the material is specified by low cycle fatigue tests. It is found that the perfect plasticity leads to greater stress relaxation. In order to propose an accurate model to compute the residual stress relaxation, the Taguchi L18 array with four 3-level factors and one 6-level is employed. Using statistical analysis, the order of factors based on their effect on stress relaxation is determined as mean stress, stress amplitude, initial residual stress, and number of cycles. In addition, the stress relaxation increases with an increase in mean stress and stress amplitude.

Behavior of HPFRC Connections for Precast Concrete Frames Under Reversed Cyclic Loading

PCI Journal ◽  
1998 ◽  
Vol 43 (6) ◽  
pp. 58-71 ◽  
Author(s):  
Rosa M. Vasconez ◽  
Antoine E. Naaman ◽  
James K. Wight
Keyword(s):  
Cyclic Loading ◽  
Precast Concrete ◽  
Concrete Frames ◽  
Reversed Cyclic Loading ◽  
Reversed Cyclic

scholarly journals Plasticity based interface model for failure modelling of unreinforced masonry under cyclic loading

2020 ◽  
Vol 42 (3) ◽  
pp. 321-338
Author(s):  
P. V. S. K. Kumar ◽  
Amirtham Rajagopal ◽  
Manoj Pandey
Keyword(s):  
Cyclic Loading ◽  
Yield Surface ◽  
Failure Modes ◽  
Back Stress ◽  
Unreinforced Masonry ◽  
Interface Model ◽  
Linear Set ◽  
Mixed Hardening ◽  
Hardening Law ◽  
Backward Integration

In this work our objective is to understand the failure behaviour of unreinforced masonry under in-plane cyclic loading. For this purpose we proposed a plasticity based interface model consists of a single yield surface criteria which is a direct extension of Mohr-Coulomb criteria with a tension cut and compression cap and a back stress vector is introduced as a mixed hardening law variable  in the adopted yield surface to capture the unloading/reloading behaviour of masonry under cyclic loading. A simplified micromechanical interface modelling approach is adopted to capture all the failure modes of masonry. The integration of the differential constitutive equation is  done by using implicit Euler backward integration approach and the obtained non-linear set of equations are solved by a combined local/global Newton solver. The proposed constitutive model  is implemented in ABAQUS by writing  UMAT (user-defined subroutine) and the obtained numerical results are compared with  experimental results available in the literature.

Reversible Transformation Plasticity in Uniaxial Tensioncompression Cycling of Mg-PSZ

1986 ◽  
Vol 78 ◽  
Author(s):  
K. J. Bowman ◽  
P. E. Reyes-Morel ◽  
I-W. Chen
Keyword(s):  
Cyclic Loading ◽  
Plastic Strain ◽  
Constitutive Relations ◽  
Constitutive Behavior ◽  
Strain Rates ◽  
Transformation Plasticity ◽  
Strain Control ◽  
Reversible Transformation ◽  
Thermally Activated ◽  
Reversed Cyclic

ABSTRACTPreviously, the pressure, temperature and strain rate sensitivities of transformation plasticity have been investigated for monotonic loading of Mg- PSZ. Research in this area has been extended to fully reversed cyclic loading of the type used in plastic strain control fatigue. Cyclic deformation experiments were performed to permit investigation of constitutive behavior under stable deformation conditions at microstrain levels. It was found that cyclic microstrains over a range of temperatures and strain rates were associated with reversible transformation plasticity in the strongly thermally-activated regime. These results are compared to the constitutive relations of transformation plasticity which have been previously developed to explain macrostrain observations.

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